At present an idle mode has been defined in WiMAX system. When a terminal enters the idle mode from an active mode, both the corresponding wireless connection thereof and the connection of an access network are released; meanwhile, the information of the terminal is saved in an anchor paging controller, thus the terminal occupies no wireless resource and the resource of the access network; the terminal which has entered into the idle mode receives downlink broadcast messages periodically, and does not need to register at a particular base station when traveling among a plurality of base stations, thus energy consumption can be saved.
No matter whether the procedure for entering the idle mode is initiated by the terminal or by the network, a paging agent will send terminal related information to the anchor paging controller of this terminal via an IM_Entry_State_Change_Request message which carries the information of this terminal required to be saved by the anchor paging controller (named as idle mode entering parameters hereinafter). The information comprises part or all of the following: an anchor paging controller identifier, an anchor authenticator identifier, an anchor gateway identifier, a current accessed base station identifier, a paging parameter, service flow information, an SBC (terminal basic capability) context, a REG (registration) context, a PKM (private key management) context, safety association description, and service flow information.
The anchor paging controller will also interact message(s) with the anchor authenticator of this terminal so as to make the anchor authenticator judge whether this terminal is allowed to enter the idle mode, upon receiving the IM_Entry_State_Change_Request message sent by the page proxy; the anchor authenticator will save the anchor paging controller identifier of this terminal only when it is determined that the terminal is allowed to enter the idle mode, further the anchor paging controller will save the above-mentioned idle mode entering parameters.
FIG. 1 is a schematic chart of the flow for a current WiMAX system terminal entering an idle mode, which comprises the following steps in particular:
101: the paging agent sends an IM_Entry_State_Change_Request message to the anchor paging controller (each anchor paging controller has one corresponding location register, and the location register records the information of the terminal in the idle mode); this message contains the parameters such as the current base station identifier, the paging parameters and idle mode reservation information; this message can arrive at the anchor paging controller via one or more relay paging controller.
102: the anchor paging controller sends the IM_Entry_State_Change_Request message to the anchor authenticator, and the anchor authenticator judges whether the terminal is allowed to enter the idle mode after receiving this message: if it is allowed, the anchor authenticator saves the anchor paging controller identifier.
103: the anchor authenticator sends an idle mode entering status change response message to the anchor paging controller; and this response message contains the judging result (result identifier) of the anchor authenticator; if the judging result indicates that the terminal is allowed to enter the idle mode, the anchor paging controller saves the above idle mode entering parameters of the terminal.
104: the anchor paging controller sends the idle mode entering status change response message to the paging agent; and this message may arrive at the anchor paging agent via one or more relay paging controllers.
In the above procedure for entering an idle mode in the current WiMAX system, no consideration is put to the mobility restriction characteristics of the terminal. The mobility restriction means that the user of a WiMAX system operator, without a mobility license, has to restrict its terminal in mobility; or that even the operator having a mobility license, the operator, in order to attract the low level users to use the WiMAX network, allows the low level users to use the WiMAX network with a low price by restricting the mobility of this type user terminal.
Therefore, by applying the current method for entering an idle mode, it is unable to judge the mobility restriction in the subsequent process procedures (for example, an idle mode exiting procedure, a location update procedure, and a procedure for re-distributing by the anchor paging controller or the anchor authenticator, etc.), which will result in the problems such as that the terminal will be erroneously allowed to exit an idle mode and enter an active mode or update its location in a non-authorized region.